Lunar Prospector is nearing the completion of its full 18 month
primary and extended missions. Many new insights into lunar science
have resulted. As the spacecraft nears the end of its useful
lifetime, a bold experiment will make a final attempt to glean a
last nugget of science from an already successful mission. A team
of scientists led by David Golstein of the University of Texas will
endeavor to smash the tiny spacecraft into a permanently shadowed
south pole crater. If all goes well in this low probability, high
pay-off attempt, a direct signal of water ice could be viewed by
land and spacebased telescopes. The crash time is 0951 UTC on July 31.

The Prospector will crash into a permanently shadowed crater on
the Lunar south pole. The crater is named Mawson. It is near the
south Pole of the moon, an area in permanent shadow. Although the
Lunar Prospector spacecraft will weigh only 354 pounds (161 kilograms)
at mission end, the energy at impact will be the equivalent of
crashing a two-ton car at more than 1,100 miles per hour.

The current plan calls for a controlled impact of the Lunar Prospector
spacecraft in the early morning hours of July 31 directly into a
small crater (Mawson), located at the southern lunar pole. This
crater is ideal for the proposed experiment. It is only 31 to 38
miles (50 to 60 kilometers) across and has a rim which is high
enough to provide a permanent shadow, yet it is low enough to
provide for a suitable spacecraft impact trajectory. Data from
other observations suggest that the crater could contain a high
concentration of water ice. Finally, the crater is observable at
impact time from Earth-based observatories and orbiting platforms.

Much of the area around the south pole is within the South Pole-Aitken
Basin (shown at left in blue on a lunar topography image), a giant
impact crater 2500 km (1550 miles) in diameter and 12 km deep at
its lowest point. Many smaller craters exist on the floor of this
basin. Since they are down in this basin, the floors of many of
these craters are never exposed to sunlight.

"The argument for targeting [the Mawson] crater is that it is both
in permanent shadow, as shown by our radar data, and also has a
high hydrogen abundance, as shown by new Lunar Prospector data.
This makes it a prime candidate for water ice deposits."

[On Rukl libration chart V],
the 1/3 semi circle (unnamed and featureless) and near crater Malapert
is crater Mawson (I think!) - it looks like it when compared to the
photos on the web pages above.